Applications characterized as “latency sensitive” are, typically, highly susceptible to execution delays and jitter (i.e., unpredictability) introduced by the computing environment in which the application runs. Examples of latency sensitive applications include financial trading systems, which usually require split-second response time when performing functions such as pricing securities or executing and settling trades.
Execution delay and jitter is often introduced by computer hardware components. For example, an application may issue input/output (I/O) requests to read data from or write data to a data storage device that can introduce unwanted latency. In addition, a slow or unreliable network connection may cause delay and/or jitter. In some cases, the operating system software running on a host may itself be a cause of delay or jitter, especially in virtualized systems, where a virtual machine running the application shares processing resources with other virtual machines and other system tasks. First, the virtual machine may be forced to wait prior to execution when there is insufficient processing resources. Further, even when the virtual machine is scheduled for execution right away, a previously executing process will need to be halted and requeued for later execution, introducing delays. There may also be situations where the virtual machine is preempted by other (higher priority) system tasks or hardware interrupts. Finally, certain system features, such as hyperthreading or frequency scaling (which provides for the adjustment of the operating speed of a physical processor based on system load) may be the source of additional delays.